linux-kernel - Re: kfree(0)

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Message-ID: <46C2CE42.4010303@gmail.com>
Date:	Wed, 15 Aug 2007 11:58:26 +0200
From:	Rene Herman <rene.herman@...il.com>
To:	Jan Engelhardt <jengelh@...putergmbh.de>
CC:	Jason Uhlenkott <jasonuhl@...onuhl.org>,
	Arjan van de Ven <arjan@...radead.org>,
	Tim Bird <tim.bird@...sony.com>,
	linux kernel <linux-kernel@...r.kernel.org>
Subject: Re: kfree(0) - ok?

On 08/15/2007 11:20 AM, Jan Engelhardt wrote:

> On Aug 15 2007 10:37, Rene Herman wrote:
>> On 08/15/2007 09:28 AM, Jan Engelhardt wrote:
>>> On Aug 14 2007 16:21, Jason Uhlenkott wrote:
>>>> On Tue, Aug 14, 2007 at 15:55:48 -0700, Arjan van de Ven wrote:

>>>>> NULL is not 0 though.
>>>> 
>>>> It is.  Its representation isn't guaranteed to be all-bits-zero,
>>> 
>>> C guarantees that.
>> 
>> C guarantees what? If you're disagreeing with Jason -- he's right.
> 
> http://coding.derkeiler.com/Archive/C_CPP/comp.lang.c/2003-11/1808.html

He said the null _pointer_ isn't guaranteed to be all-bits zero. And it 
isn't. Read the standard or the faq.

>>>> but the constant value 0 when used in pointer context is always a
>>>> null pointer (and in fact the standard requires that NULL be
>>>> #defined as 0 or a cast thereof).

Rene.
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